People access more and more information through Internet services. On many occasions such services store data, such as user interface settings, about their users in order to serve them better. Storing more data about a user enables the service to provide a better experience to that user, as the service operation can then be better tailored to that user's needs, preferences, and expectations. Storing data about a user, however, can lead to various issues, such as security and privacy concerns.
It would be desirable for Internet services to strongly protect the security and privacy of user information while improving the user experience by storing additional user-specific information. To achieve these goals, such services should be capable of storing arbitrarily large amounts of data associated with a user while ensuring that the data related to a particular user can be accessed only while servicing requests from that user.